EXPLANATION

Universal Transverse Mercator projection, Zone 15

Horizontal coordinate information referenced to the 

North American Datum of 1983 (NAD 83)

0 1 2 MILES

0 1 2 KILOMETERS

Sediment thickness measuring point

and sediment thickness, in feet

2.5

Sediment core sample colocated

 with sediment thickness measuring

 point and core thickness, in feet

2.3

Figure 4. Sediment thickness zones and measurement locations in Millwood Lake 

near Ashdown, Arkansas, March 2013.

Zone 1

30 points

mean=2.3 feet

area=4,590 acres 

Zone 5

23 points

mean=4.9 feet

area=4,560 acres 

Zone 4

14 points

mean=5.7 feet

area=3,720 acres 

Zone 3

27 points

mean=2.2 feet

area=8,050 acres 

Zone 2

35 points

mean=3.0 feet

area=5,070 acres 

2.4

2.3

2.6

1.5 1.4

0.5

2.4 1.4

0.7 1.3 2.5 2.3 3.6

2.2 3.0 1.2

2.7 3.2 2.5

2.5

3.1 2.8

3.0 3.3

6.2

3.8

4.8 1.9 7.3

1.2

1.4 1.5 2.3

5.6 5.1

1.6

1.7 4.6

2.5

9.0 4.8

11.0

4.5

5.4

1.6 0.5 2.4

4.2 1.3 3.1

3.8 3.6 6.0 0.8

3.9 3.2 3.1 4.4

5.8 4.1 2.2 3.6 13.3

2.6 0.7

1.3

3.9

4.8

1.3

1.6

5.0

1.5 1.5

1.5 2.0

3.0 3.8 3.0 1.0

3.1 4.4 3.3 2.6

2.0

1.2 2.1

1.8

1.5

2.7

7.2

3.7

4.3

5.3

5.6

5.2

4.2

2.8

3.4

2.2

0.8

1.7

3.0 0.8

4.3

2.9

7.4

8.7

1.2

2.3

1.9

1.6 4.5

2.0

6.0

4.6

2.5

4.2

2.2

0.0 3.0 1.8

14.3

3.0

2.5 3.0

2.5

12.6

2.0

3.3

2.0

0.9 2.0

2.3

5.0 2.8

2.7

1.6

1.7

2.9

93°56'

93°56’

93°58’

93°58’

94°00’

94°00’

94°04’

94°06’

94°10’

33°48'

33°48'

33°46’

33°46'

33°42' 33°42’

33°42’

33°48’

Universal Transverse Mercator projection, Zone 15

Horizontal coordinate information referenced to the North 

American Datum of 1983 (NAD 83)

Elevation information referenced to the North American 

Vertical Datum of 1988 (NAVD 88)

250

240

230

EXPLANATION

Millwood Lake

RP1

Bathymetric index contour—Shows elevation of the lake bottom. 

Contour interval 10 feet. Elevations referenced to North American 

Vertical Datum of 1988 (NAVD 88). Contours tested 5.81-foot 

vertical accuracy at 95-percent confidence level.

U.S. Geological Survey reference marker and identifier—

RP1-chiseled arrow on east edge of boat ramp; elevation is 

259.86 feet. RP4-chiseled arrow on northwest corner of concrete 

pier on the boat ramp walkway; elevation is 260.43 feet.

Water surface—Shows approximate mean water-surface elevation 

March 3–20, 2013 (259.5 feet, table 1). Elevations referenced to 

North American Vertical Datum of 1988 (NAVD 88).

0 1 2 MILES

0 1 2 KILOMETERS

Bathymetric contour—Shows elevation of the lake bottom. Contour 

interval 2 feet. Elevations referenced to North American Vertical 

Datum of 1988 (NAVD 88). Contours tested 5.81-foot vertical 

accuracy at 95-percent confidence level.

Figure 3. Bathymetric contours for Millwood Lake near Ashdown, Arkansas, resulting from surveys made March 3–20, 2013.

RP1

RP4

Millwood Lake Dam

230

250

250

250

230

250 250

240

250

250

250

250

250

250

250

250

250

250

230

240

250

250

250

240

250

250

250

240

230

250

250

230

240

240

250

230

240

230

250

250

230

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5

259.5 259.5

93°56’ 93°58’ 94°00’

94°06’ 94°02’

94°08’ 94°10’

33°48’

33°48’

33°46'

33°44’

33°42'

33°46’

94°04’

33°44’

94°02’

33°42’

93°56’

33°46’

EXPLANATION

Data-collection points on transect lines

Quality-assurance data-collection points 

 on transect lines

Individual target data-collection point

Universal Transverse Mercator projection, Zone 15

Horizontal coordinate information referenced to the 

North American Datum of 1983 (NAD 83)

0 1 2 MILES

0 1 2 KILOMETERS

Figure 2. Data-collection points for Millwood Lake near Ashdown, Arkansas, 2013.

93°56’

93°58’ 93°56’

94°00’

94°02’ 94°00’ 94°04’

94°06’

94°10’ 94°08’ 94°06’

33°48’

33°48’

33°46’ 33°46'

33°44'

33°42’ 33°42’

0 1 2 3 4 5 MILES

0 1 2 3 4 5 KILOMETERS

Ashdown

94°12’ 94°08’ 94°04’ 94°00’ 93°56’

33°48’

33°44’

33°40’

Arkansas

Study area

Figure 1. Location of Millwood Lake near Ashdown, Arkansas.

Saline River

Little

River

Millwood Lake Dam

Base from U.S. Geological Survey digital raster graphic, 1996, 1:100,000

Universal Transverse Mercator projection, Zone 15

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY Prepared in cooperation with 

U.S. ARMY CORPS OF ENGINEERS

SCIENTIFIC INVESTIGATIONS MAP 3282

Richards, J.M., and Green, W.R., 2013, Bathymetric map, area/capacity table,

and sediment volume estimate for Millwood Lake near Ashdown, Arkansas

Bathymetric Map, Area/Capacity Table, and Sediment Volume Estimate for Millwood Lake near Ashdown, Arkansas, 2013

By

Joseph M. Richards and W. Reed Green

2013

Introduction Quality Assurance

Millwood Lake, in southwestern Arkansas, was constructed and is operated by the U.S. Army Corps of Engineers (USACE) for flood-risk Accuracy of the bathymetric surface and contours is a function of the survey data accuracy, density of the survey data (transect interval and 

reduction, water supply, and recreation (U.S. Army Corps of Engineers, [n.d.]; fig. 1). The lake was completed in 1966 and it is likely that with time data-collection frequency), and the processing steps involved in the surface and contour creation. Onsite, a bar check, consisting of fathometer 

sedimentation has resulted in the reduction of storage capacity of the lake (U.S. Army Corps of Engineers, 2012). The loss of storage capacity can measurements of depth to a suspended steel plate, was made at the beginning of each day of data collection following established protocols (U.S. 

cause less water to be available for water supply, and lessens the ability of the lake to mitigate flooding. Excessive sediment accumulation also Army Corps of Engineers, 2002; Wilson and Richards, 2006) to ensure that the fathometer was calibrated correctly. The water-surface elevation was 

can cause a reduction in aquatic habitat in some areas of the lake. Although many lakes operated by the USACE have periodic bathymetric and determined at established reference markers as vertical controls (fig. 3) to ensure an accurate computation of reservoir-bottom elevation. Survey 

sediment surveys, none have been completed for Millwood Lake (U.S. Army Corps of Engineers, 2012). In March 2013, the U.S. Geological Survey fathometer data accuracy also is dependent on factors such as vessel draft/index errors, platform stability, vessel velocity, and subsurface material 

(USGS), in cooperation with the USACE, surveyed the bathymetry of Millwood Lake to prepare an updated bathymetric map and area/capacity density (Wilson and Richards, 2006). 

table. The USGS also collected sediment thickness data in June 2013 to estimate the volume of sediment accumulated in the lake. Quality-assurance bathymetric data were collected on transects spaced apart approximately five times the transect interval distance. Transects 

were approximately 1,640 ft apart in the south part of the lake and 3,280 ft apart in the north part of the lake (fig. 2). There were approximately 

Study Area 454,000 data points collected along the 78 miles of quality-assurance transect lines. The quality-assurance bathymetric data were resampled to 

approximately 164,000 data points using the same GIS techniques that were used on the bathymetric survey data. The three-dimensional bathymetric Millwood Lake is located on the Little River about 7 miles northeast of Ashdown, in southwestern Arkansas (fig. 1). The Millwood Lake Dam was surface was tested against the quality-assurance dataset to determine the accuracy of the surface using methods described in Wilson and Richards constructed approximately 5 river miles downstream from the confluence of the Little River that flows into the lake from the west and the Saline (2006). The surface tested 2.21 ft vertical accuracy at the 95-percent confidence level. The contours (fig. 3) also were tested with the quality- River that flows into the lake from the north (fig. 1) and approximately 16 miles upstream from the confluence of the Little River and the Red River assurance dataset and a point was considered a contour elevation evaluation point if it was located within 3.28 ft of a given contour line. Of the (not shown on map). The basin area upstream from the dam is approximately 4,144 square miles and consists of approximately 68 percent forest, 14 approximately 164,000 quality-assurance points collected, 5,283 points were considered an evaluation point for the contour lines, and the contour percent pasture, 9 percent herbaceous cover, and 9 percent is a combination of urban land use, water, and cropland (Arkansas Natural Resources vertical accuracy was computed to be 5.81 ft at the 95-percent confidence level. Commission, [n.d.]). The surficial geology of the basin consists of the dominantly clastic sedimentary rock of the Tokio Formation, Woodbine A total of 359 sediment thickness measurements were made for this study at 132 locations. Measurements were repeated multiple times (usually Formation, and the Trinity Group overlain by alluvium and terrace deposits near the lake, and Stanley Shale in the northern part of the basin (Haley, three at any given location) to determine the variation in the measurement method. The standard deviation of the differences between the measured 1993). values and the mean of the measured values at each location was 0.67 ft. Using techniques and technology available at the time of construction in 1966, it was estimated that the Millwood Lake Dam flooded approxi- Core samples (fig. 4) were collected periodically using a 60-inch Ogeechee corer with acrylic liner as a quality-assurance measure of overall mately 29,000 acres at the conservation pool elevation of 259.2 feet (ft) relative to the National Geodetic Vertical Datum of 1929 (NGVD 29). The sediment thickness sampling to support physical measurement of thickness using the refusal method. The core sampler was pushed into the bed capacity was computed at the time to be 172,000 acre-feet (acre-ft) at the conservation pool elevation (U.S. Army Corps of Engineers, 2013). The sediments by hand using vertical extensions screwed onto the head of the Ogeechee corer. When the corer could not be pushed any deeper, the lake had approximately 20,000 acres of timber (about 70 percent of the lake area) when impounded in 1966. Much of the timber has broken off at the sampler was removed from the lake sediment and the acrylic liner was removed from the core tube. The liner was then capped on the bottom, sawed conservation pool elevation, leaving many stumps and break-offs scattered throughout the lake. There are narrow boat lanes that are free from off a couple inches above the top of the core, drained, and capped at the top. Sediment height inside the core liner was recorded. Core samples were timber, allowing navigation through the timbered areas of the lake, and the area near the dam largely is free from submerged timber. collected at 10 sites and core sample lengths compared favorably with the sediment thickness data of the refusal method measurement points (fig. 

Methods 4). The process of coring the sediment caused the sediment to compact in the core barrel, so the core length was always less than the sediment 

thickness measured with the probe refusal method. The mean difference between the sediment probe thickness and the sediment core length for the 

A bathymetric survey was conducted during March 2013 and was followed up with a sediment thickness probing survey in June 2013 at 10 sites was 1.6 ft.

Millwood Lake. The general method of bathymetric data collection was using fathometer measurements of water depth, and the general method of 

sediment data collection was direct measurement of sediment thickness at dispersed points throughout the lake. Bathymetry, Capacity, and Sediment Volume Estimate

Bathymetry In an effort to verify the original Millwood Lake capacity reported by the USACE, the pre-inundation topographic data from 1:24,000 scale USGS 

Bathymetric data (water depths and positions) were collected from March 3 to March 20, 2013 (fig. 2), using methods described in Wilson and quadrangle maps of the area (data on file at U.S. Geological Survey, Rolla, Missouri) were digitized and a legacy bathymetric surface was created. 

Richards (2006). Position data were collected using a boat-mounted differential global positioning system (DGPS). Water depths were collected The same methods of volume computation used for the current (2013) survey data were used on this legacy surface to compute an estimated original 

using a survey-grade 200-kilohertz single-beam fathometer emitting sound pulses that were reflected off the lake bottom and received by a lake capacity of approximately 200,000 acre-ft at the conservation pool elevation of 259.2 ft. The methods that were used to determine the original 

transducer. In some areas of the lake, water depths were measured manually (target data-collection points; fig. 2) using a rod graduated in tenths bathymetry and capacity of the lake are unknown, but the capacity of 172,000 acre-ft computed by the USACE in 1966 does compare favorably, within 

of a foot, because the water depth was below the minimum operating depth of the fathometer, which is approximately 2.5 ft. Water-surface edge 14 percent, to the capacity obtained using data from the pre-inundation topographic data. 

points were collected using the DGPS coordinate data with zero depth. A bathymetric surface was created from the current (2013) surveyed data (fig. 2) and an area/capacity table was computed from the surface 

Reference water-surface elevations were measured from at least one of two reference points (RP1 and RP4 on fig. 3) at least twice daily, and a (table 1). At the conservation pool elevation of 259.2 ft, the surface area of the lake is approximately 26,000 acres and the capacity is approximately 

mean water-surface elevation for the day was computed from these measurements. The reference points were established with a survey-grade 188,000 acre-ft (table 1). The lake bathymetric contours show that the Little River channel is still present and is still well defined (fig. 3). Many of the 

Global Navigation Satellite Systems (GNSS) using methods documented in Rydlund and Densmore (2012) and Wilson and Richards (2006). tributary stream channels are evident in the lake bathymetric map as well. In the north part of the lake, the bathymetric surface appears to be gently 

Horizontal and vertical coordinates of the reference points were established using real-time and static GNSS methods that were localized to sloping to the south. The topographic expression of many of the small tributary channels that were mapped on the 1:24,000 scale topographic maps 

confident geodetic control. The water-surface elevation ranged from 259.37 ft to 259.66 ft during the survey period, and the computed mean (data on file at the U.S. Geological Survey, Rolla, Missouri) has been muted. It is suspected that sediment deposition has partially or completely filled 

water-surface elevation of the lake was 259.50 ft during the survey period. The reference points were not used to establish or verify horizontal in some of the defined channels that were present on the 1:24,000 scale topographic maps, resulting in a less detailed (muted) topographic surface in 

position of the bathymetric survey points. the north part of the lake (fig. 3).

The bathymetric survey was designed to collect data along transects roughly oriented northwest to southeast and at an interval that would For the sediment volume estimate, the lake was divided into five zones of similar sediment thickness (fig. 4). Zone 1 (northwest part of the main 

provide sufficient data to produce a bathymetric surface (fig. 2). Water-depth data were collected with the fathometer along the transect lines lake body) had a mean thickness of 2.3 ft, zone 2 (northeast part of the main lake body) had a mean thickness of 3.0 ft, zone 3 (the west, south, and 

spaced approximately 328 ft apart in the southeast part of the main body of the lake, and approximately 656 ft apart in the northwest part of the east part of the main lake body) had a mean thickness of 2.2 ft. Zone 4 (center of main lake body; mean thickness 5.7 ft) and zone 5 (west part of the 

main body of the lake (fig. 2). Transect lines were spaced approximately 328 ft apart (fig. 2) in the Little River arm of the lake (fig. 1). The transects lake; mean thickness 4.9 feet) had the greatest sediment thickness. Mean sediment thickness was the greatest in zone 4 possibly because of 

were farther apart in the north part of the lake because it was shallower, had less bathymetric relief, and had more near-surface obstructions to resuspension of sediment from other shallower parts of the lake and subsequent deposition in the deeper and probably calmer water in the center of 

navigation. Approximately 3,340,000 data points along the approximately 490 miles of surveyed transect lines were collected in the survey. The the lake. In zone 5, sediment thickness also was greater than the thickness in some of the other parts of the lake and the increased thickness likely is 

mean spacing of data points along a transect line was 1.3 ft. The position data for the fathometer data were used as collected from the DGPS with because of its proximity to the inflow of the Little River, the primary source of sediment to the lake. It should be noted that the measured values were 

a stated positional accuracy of less than 3.28 ft (Trimble Navigation Limited, 1999). The vertical datum for the survey was the North American assumed to be the result of sediment deposition after the lake was impounded. It is possible that many, if not most, of the sediment measurements 

Vertical Datum of 1988 (NAVD 88) and the horizontal datum was the North American Datum of 1983 (NAD 83). include some unknown measure of pre-impoundment sediment.

Water-depth data were converted to lake-bottom elevations by subtracting the depth at each location from the reference water-surface Sediment volume for each zone was computed by multiplying the mean sediment thickness by the area of the zone at the conservation pool 

elevation of the lake for the day the point was collected. Geographic information system (GIS) software was used to resample the bathymetric data elevation of 259.2 ft. The total sediment volume of the lake was computed by summing the volume in each zone, and was approximately 87,000 acre-ft. 

points so that the points would be no closer than approximately 2 ft apart. The data reduction retained approximately 788,000 data points. These The mean sediment thickness, computed by dividing the total sediment volume by the surface area of the lake at the conservation pool elevation, 

bathymetric data points were used to produce a three-dimensional surface of the lake-bottom elevations using the techniques described in Wilson was approximately 3.3 ft. On average, approximately 1,850 acre-ft or 0.07 vertical ft of sediment was deposited in the lake per year. 

and Richards (2006). The boundary of the lake at the time of the survey was estimated from aerial imagery (Google Earth, site accessed May 2013), Although the exact original volume of the lake is unknown, it probably ranges between about 200,000 acre-ft (obtained from the pre-inundation 

surveyed edge point data, and USGS digital elevation data (http://ned.usgs.gov/). An area and capacity table was produced from the legacy bathymetric surface) and 275,000 acre-ft (the total of the lake capacity at the conservation pool elevation and sediment volume for this survey). 

three-dimensional surface (table 1) showing surface area and capacity at specified elevations. The surface was contoured at a 2-ft interval using Given the estimated volume of sediment in the lake, the loss of capacity in Millwood Lake during the last 47 years ranges between about 32 and 

GIS software and the contours were cartographically edited to create a bathymetric map using the techniques of Wilson and Richards (2006; fig. 3). 44 percent, which is about 0.7 to 0.9 percent per year. Because of the possibility of pre-inundation sediment in the sediment thickness measurements, 

the volume and capacity loss estimates given here should be considered an upper limit for the lake. Sediment Thickness Measurement

Before being impounded, the Little River was a sinuous, low-gradient river with a deep, well defined channel and numerous oxbow lakes and References Cited

marshes adjacent to the main channel as shown on 1949 aerial photography (data on file at U.S. Geological Survey, Rolla, Missouri). Because the 

area was a riverine environment before being impounded, sediment potentially accumulated in the channel and, in times of high flow, on overbank Arkansas Natural Resources Commission, [n.d.], Arkansas Watershed Information System: Arkansas Natural Resources Commission, accessed 

areas. Determination of the depth of sediment that is only the result of deposition after the lake was created is very difficult and cannot be November 2013, at http://watersheds.cast.uark.edu/viewhuc.php?hucid=11140109.

determined using the methods described in this report. Nevertheless, all sediment thicknesses measured during this study were assumed to be the Haley, B.R., 1993, Geologic map of Arkansas: U.S. Geological Survey map sheet, scale 1:500,000. result of sediment deposition in the lake. Juracek, K.E., 2006, Sedimentation and occurrence and trends of selected chemical constituents in bottom sediment, Empire Lake, Cherokee County, To determine sediment thickness accumulated during the past 47 years in the lake since 1966, physical measurements were made spatially at Kansas, 1905–2005: U.S. Geological Survey Scientific Investigations Report 2006–5307, 79 p. 132 locations throughout the lake using the sediment probe refusal method (Juracek, 2006; fig. 4). Water depth greater than about 25 ft prevented 

measurement of sediment thickness in some areas of the lake. In most cases, the point of refusal was marked by a red clay layer evident on the Rydlund, P.H., Jr., and Densmore, B.K., 2012, Methods of practice and guidelines for using survey-grade global navigation satellite systems (GNSS) to 

sediment probe. A spatially representative sample of measurements was made on a 2,640-ft grid (fig. 4) in the north part of the main body of the establish vertical datum in the United States Geological Survey: U.S. Geological Survey Techniques and Methods, book 11, chap. D1, 102 p. with 

lake. Measurements were made on a 5,280-ft grid in the south part of the main body of the lake (fig. 4). It was assumed that the sediment thickness appendixes.

would be less in the south part of the main body of the lake because it was farthest from the sediment source areas. Thus, grid spacing was larger Trimble Navigation Limited, 1999, AgGPS 124/132 Operation Manual, Revision B: Overland Park, Kansas, Trimble Precision Agricultural Systems, 218 p.

in that area. In the Little River arm of the lake (figs. 1, 4), several measurements were made where possible to provide an estimate of the sediment U.S. Army Corps of Engineers, 2002, Engineering and design—Hydrographic Surveying: Washington, D.C., Engineer Manual No. 1110–2–1003, 510 p. thickness for that part of the lake. U.S. Army Corps of Engineers, [n.d.], Dam and lake information: accessed March 2013, at The sediment probe refusal method used a probe consisting of a length of 3⁄4-inch threaded steel rod that was pushed by hand from a boat into 

http://www.swl.usace.army.mil/Missions/Recreation/Lakes/MillwoodLake/DamandLakeInformation.aspx. the sediment to the point of refusal. The probe was removed and the depth of sediment penetration was measured from the sediment accumulated 

on the threaded rod. The process usually was repeated two additional times within approximately 15 feet of the initial measurement at most of the U.S. Army Corps of Engineers, 2012, Millwood Lake Fact Sheet: accessed March 2013, at 

measurement sites to determine the magnitude of the variation in the measurements. The mean of all the measurements taken at each site was http://www.swd.usace.army.mil/Portals/42/docs/FY13%20Millwood%20Lake,%20AR.pdf.

used as the sediment thickness value, and is shown on figure 4. U.S. Army Corps of Engineers, 2013, National Inventory of Dams: accessed July 2013, at http://geo.usace.army.mil/pgis/f?p=397:1:0. Based on the variance in sediment thickness, sediment-thickness data were grouped spatially and sediment-deposition zones were delineated Wilson, G.L., and Richards, J.M., 2006, Procedural documentation and accuracy assessment of bathymetric maps and area/capacity tables for small in the lake (fig. 4). Inside each zone, the mean of the physically measured sediment-thickness values was used with the surface area of the region lakes: U.S. Geological Survey Scientific Investigations Report 2006–5208, 24 p. to determine an estimate of sediment volume for that zone. 

Table 1. Area and capacity at specified 

elevations for Millwood Lake near Ashdown, 

Arkansas, March 3–20, 2013.

[Conservation pool elevation is 259.2 feet; the average 

water-surface elevation during the survey was 259.5 feet; 

elevations are referenced to the North American Vertical 

Datum of 1988 (NAVD 88); volumes calculated from surface 

testing 2.21-foot vertical accuracy at 95-percent confidence 

level]

Elevation, Area, Capacity, 

 in feet in acres in acre-feet

 223.0 0.23 0.09 

 224.0 1.47 0.81 

 225.0 4.64 3.63 

 226.0 10.5 11.0 

 227.0 19.0 25.4 

 228.0 34.3 51.4 

 229.0 60.1 97.4 

 230.0 96.1 175 

 231.0 140 292 

 232.0 196 460 

 233.0 247 681 

 234.0 298 954 

 235.0 349 1,280 

 236.0 407 1,650 

 237.0 468 2,090 

 238.0 536 2,590 

239.0 602 3,160 

 240.0 671 3,800 

 241.0 754 4,510 

 242.0 854 5,310 

 243.0 978 6,220 

 244.0 1,130 7,270 

 245.0 1,340 8,510 

 246.0 1,620 9,980 

 247.0 1,970 11,800 

 248.0 2,440 14,000 

 249.0 3,530 16,900 

 250.0 6,120 21,600 

 251.0 9,780 29,500 

 252.0 12,800 40,900 

 253.0 15,700 55,200 

 254.0 18,000 72,100 

 255.0 19,800 91,000 

 256.0 21,500 112,000 

 257.0 23,200 134,000 

 258.0 24,300 158,000 

 259.0 25,800 183,000 

 259.2 26,000 188,000 

 259.5 26,500 196,000 

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government.

Suggested citation: Richards, J.M., and Green, W.R., 2013, Bathymetric map, 

area/capacity table, and sediment volume estimate for Millwood Lake near 

Ashdown, Arkansas, 2013: U.S. Geological Survey Scientific Investigations 

Map 3282, 1 sheet, http://dx.doi.org/10.3133/sim3282.

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3282